Did GM put date codes on old water pumps and where.. Lotsa "Bubba" rattle can paint on the 2608 unit but I can make out a 6 with an "M" in a square.On the other pump, I see a "GM 3" on the front, and when I turn it over "S3" is stamped on the rear.. The 2609 pump has a fitting somewhat like a BBC on the middle of the pump and the 2608 pump has a fitting 45 degree angled to the psgr. side... Any idea of the dates of these beasts and, what is best way to clean these e.g. media blast without marring the pumps... Thanks!! T.

Saginaw-cast 608's usually have the date code on the front of the driver's side leg, and Tonawanda-cast 608's usually have it directly below the weep hole in the snout. A raised "S" on the engine side of the casting (inside the pump, in the impeller area) says it's a Saginaw casting.

Thanks encore John!!! What is the besy way to clean the pumps?? If media blasting - what kind?? Is the Saginaw pump a Vette unit, C2, maybe and why was the fitting placed on the top akin to a BBC pump? T.

Is the Saginaw pump a Vette unit, C2, maybe and why was the fitting placed on the top akin to a BBC pump? T.

The 608 pump was used on lots of SB applications for many years, including Corvettes. The boss and fitting at the top of the other pump was for a bypass hose to the front of the intake manifold; all 1963-67 carbureted small-block Corvettes with aluminum intakes and 63-65 fuelies used the intake bypass hose.

My question is about which is correct and is there a preference as to sag or ton as well as date codes?

For Z/28's, they have to be Saginaw castings; for everything else, the block and water pump have to be from the same foundry source (the engine plants machined/manufactured the water pumps from raw castings).